646408 has 48 divisors (see below), whose sum is σ = 1508220. Its totient is φ = 258048.

The previous prime is 646403. The next prime is 646411. The reversal of 646408 is 804646.

It can be written as a sum of positive squares in 2 ways, for example, as 636804 + 9604 = 798^2 + 98^2 .

It is a Harshad number since it is a multiple of its sum of digits (28).

It is not an unprimeable number, because it can be changed into a prime (646403) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6616 + ... + 6712.

2⁶⁴⁶⁴⁰⁸ is an apocalyptic number.

646408 is a gapful number since it is divisible by the number (68) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (754110).

646408 is an abundant number, since it is smaller than the sum of its proper divisors (861812).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

646408 is a wasteful number, since it uses less digits than its factorization.

646408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134 (or 123 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 646408 is about 803.9950248602. The cubic root of 646408 is about 86.4640500147.

The spelling of 646408 in words is "six hundred forty-six thousand, four hundred eight".